Project Summary/Abstract Anxiety and mood dysregulation are impairing, often persistent emotional difficulties in preschool-aged children that cause substantial personal, familial, and economic burden over time. However, these behaviors are developmentally normative in young children, and the level at which such behaviors may be clinically significant is largely unknown. Without established norms identified with developmentally sensitive methods over time, it is difficult to distinguish mild, transient behaviors from risk for persistent, impairing psychopathology. The proposed renewal project will follow-up with a sample of 3-5-year-old children when they are 6-8-years-old using multi-method assessment to generate norms of early anxiety and mood dysregulation and map individual differences and patterns of behavior, family environment, and stress physiology. A novel daily diary method will assess the daily frequencies of internalizing behaviors, a diagnostic interview will assess children?s symptomatology and functioning, and teacher report will provide information about children?s behavior at school. In a subsample, correlates of psychopathology will be assessed to validate the internalizing phenotypes and further clarify normative and problematic behavior, including child observed and self-report behavior, parental psychopathology and parenting behavior, and family stressors along with acute and chronic stress physiology, specifically salivary inflammatory markers (C-reactive protein and cytokines) as well as cumulative hypothalamic pituitary axis cortisol activity measured via hair samples, respectively. Follow-up information about children?s functioning in early school age is vital for characterizing the spectrum of behavior and clarifying variation in behavior that increases clinical risk for psychopathology in preschool age. These efforts will advance the NIMH mission to better understand mental illness trajectories and know whether and when to intervene, as early as possible. In particular, the work is aligned with NIMH Strategic Objective 2 that calls for clarification of the spectrum of typical to atypical development to characterize mental illness risk early in life. Knowledge gained from this proposal will significantly advance the field by 1) providing developmentally sensitive information on the phenomenology of early-emerging psychopathology over time, 2) advancing the transdiagnostic, dimensional approach by assessing the full variation of anxiety and mood dysregulation, and 3) identifying biomarkers that reflect early deviation in emotional development over time, 4) utilizing data collected in early school-age for informing which preschool-aged children would benefit from prevention and intervention efforts for emerging internalizing psychopathology. Importantly, consistent with the R15 mechanism, this study will continue to strengthen the PI?s institution?s research environment by providing students in-depth experience with multi-method, longitudinal research in developmental psychopathology.